Wintersowing 2011 Wrapup: What worked and lessons learned

In January and February, I set out a series of recycled plastic water containers filled with potting soil and sown with seed that could undergo or absolutely required cold stratification. I did a tally the other day to see how my wintersowing experiment went.

I was disappointed. Some seed performed excellently and a few did OK. But overall, most seeds had very poor germination rates (20% or less) or failed to germinate at all. I was shocked at the no-shows from what I would have thought were surefire wintersowing successes like the New England Aster and two of the three Asclepias species.

Wild chicory, one of the rare seeds liked wintersowing

It's possible that one contributing factor is the unusually wet and cold spring we have had; I read Monday that Montréal experienced double the average precepitation for this time of year. As a consequence, the potting soil was wet for prolonged periods of time and a lot of the containers became green with moss or (what is possibly) algae. I can see how the plants preferring quicker drainage would be unhappy.

Mossy!

Another possibility is seed source. All of the alpines were from Rocky Mountain Rare Plants' (RMRP) going out of business sale. None of them have been great performers wintersown or under lights (but worse when wintersown), despite many of them sold as easy 70°F germinators.

Amusingly enough, a few of the ungerminated pots surprised me with sprouts Monday morning when I went  to throw them out. This convinced me enough to keep some of the other containers with no apparent germination around for a little longer (**).

Would I repeat the experience? I'm not sure.

I would definitely plan better if I did it again. I struggled to find somewhere to plant the abundance from the excellent performers. The early emergence of the spinach and bok choy in April caught me completely off guard -- they bolted before I could get them in the ground as it were.

Happy bok choy, spinach, red orach

I would probably make up a custom, soilless mix rather than bagged el-cheapo potting mix to better control drainage and unwanted fungus / moss / algal growth. When it became clear that my containers were waterlogged, I found it difficult to add drainage with it already full of medium; it would be far easier to tape over extra drainage holes to reduce drainage than to make new ones.

But mostly, the large number of poor performers tempered any joy I had from seeing the other sprouts emerge even though I know that some of these might be hard to germinate under any circumstances.

The one huge benefit to wintersowing is virtually eliminating the need to harden off the little guys since they were exposed to the sun's deadly rays from the beginning (the containers were uncapped). I've managed to kill off or damage a not insignificant amount of seedlings grown under lights while hardening them off (and, it seems, the more precious the seedling to me, the more likely it would die a quick UV death) this spring. I've had zero deaths from hardening off in the wintersown bunch. To be extra cautious, I let them acclimatize to the elements for a couple of days by removing the duck tape keeping them shut, and then cut off the top of the containers altogether.

WINTERSOWING 2011 RESULTS (full spreadsheet here)
Excellent (80-100% germination)
Harebell (Campanula rotundifolia)
Black-eyed Susan (Rudbeckia fulgida 'Goldsturm')
Shasta Daisy (Leucanthemum × superbum 'Alaska')
Blanket flower (Gaillardia × grandiflora 'Goblin')
Milkweed (Asclepias syriaca) *
Rampion (Campanula rapunculus)
Chicory (Cichorium intybus)
An aster of some kind (100-0670) *
Spinach (Spinacia oleracea)
Bok choy (Brassica rapa chinensis)
Red orach (Atriplex hortensis)

OK (50-79% germination)
Mystery peanut pod seeds (100-1046) *
Prairie gayfeather (Liatris spicata)

Poor (1-49% germination)
Echinacea (Echinacea purpurea)
Mystery flower pod (100-0660) *
Prairie crocus (Pulsatilla patens) (RMRP) ***
Black pasque flower (Pulsatilla pratensis subsp. nigricans) (RMRP) ***
Pulsatilla campanella (RMRP) ***
Teasel (Dipsacus sylvestris) *
Blackberry lily (Belamcanda chinensis)
Caucasian Bellflower (Campanula bellidifolia) (RMRP)
Gunnison's mariposa lily (Calochortus gunnisonii) (RMRP)
Avery peak twinpod (Physaria alpina) (RMRP)
Tibetan blue poppy (Meconopsis betonicifolia) ***

Failed to germinate
Alp lily (Lloydia serotina) (RMRP) **
Alpine kittentail (Besseya alpina) (RMRP) **
Stemless gentian (Gentiana acaulis) (RMRP) **
Butterfly weed (Asclepias tuberosa)
New England aster (Symphyotrichum novae-angliae)
Blue Queen salvia (Salvia × superba)
Prairie coneflower (Ratibida pinnata) **
Bottle gentian (Gentiana andrewsii) **
Swamp milkweed (Asclepias incarnata)

* Personally wild-collected
** Second chance
*** Provisional pending ID of seedling (is it a weed lookalike or not?)